1. Field of the Invention
This invention relates to metal fiber structures and more particularly to molded metal fiber structures.
2. Description of the Prior Art
Abradable seals made from metal fibers have been used to seal various areas in rotary compressors and in turbine engines and their compressor sections, including the space between the turbine blade tips and the engine housing and the space between the turbine shaft and the turbine vanes.
These seals must provide sufficient abradability, gas flow blockage and erosion resistance. Increasing density enhances erosion resistance and gas flow blockage but it adversely affects abradability. Similarly, increasing tensile strength enhances erosion resistance, but adversely affects abradability.
The prior art seals are fabricated by working with a flat brittle porous sheet of sintered metal fibers. The sheet is cut to size and a reinforcing backing is welded to it or it is brazed into a ring. An undesirable "butt joint" results in the ring seal due to the welding or brazing operations. In these prior art seals there is a random orientation of the fibers in the porous sheet which cannot be changed once the sheet is formed. Also, the density throughout the sheet and hence throughout the resulting seals is substantially uniform.